Wehavecarriedouthighlevelgasphasequantumchemical calculations of the relative energetics of the alanine tetrapeptide, using the SP2 obtained as part of the CUCBS facility. These calculations allow, for the first time, an evaluation of the performance of a wide variety of molecular mechanics force fields for the peptides as compared to accurate quantum chemistry. Work currently in progress involves examination of a wide range of different amino acids and peptide structural motifs, as well as extention of the approach to solution phase comparisons. A. Scientific Subproject